According to the rapid miniaturization, weight lightening and high performance establishment of electronic products, electronic equipments, and communication equipments, the performance improvement of a lithium secondary battery used as the power source thereof is greatly required.
A lithium secondary battery includes a cathode including an electrode active material, a binder and a conductive material as main components, an anode, a separator disposed between the cathode and the anode, and an electrolyte.
In the anode, since a carbon-based material as the electrode active material has high conductivity in itself, the carbon-based material may play the role of the conductive material at the same time. However, according to the progress of charging and discharging, an anode active material may react with lithium ions, and an electron moving path may become unstable. To supplement this defect, a separate conductive material is additionally necessary.
As described above, the basic performance of a lithium secondary battery is dependent greatly on the properties of a material such as an electrode active material, a conductive material, etc.
Particularly, a conductive material plays the role of improving electrical conductivity between electrode active materials, or an electrode active material and a current collector. In the case that the amount of the conductive material is insufficient, or the role thereof is improperly conducted, unreacted portion in the electrode active material may increase, and battery capacity may decrease. In addition, high speed charging and discharging properties, high-rate charging and discharging efficiency and initial charging and discharging efficiency may be negatively influenced.
Generally, a dot type conductive material such as acetylene black or carbon black has been used as the conductive material, however in this case, high-rate discharging properties and initial charging and discharging efficiency are low, and the loss of an electrode active material may be generated.
Accordingly, the development of a conductive material for a secondary battery for improving charging and discharging efficiency, etc. is urgently needed.